Jean described two newly discovered X-ray burst phenomena: (1) long burst tails, (2) superexpansion bursts.
Long burst tails:
-- by stacking bursts from the clocked burster GS 1826-24, can now detect ~hour long tails in its ~100 sec. long type I X-ray bursts. These tails are due to heat propagating out on long time scales and match tails seen in the Heger et al. 2007 burst calculations.
-- puzzle: some bursts show tails with a fluence that is larger than the fluence of the flash itself, suggesting that more heat goes down than goes out. Is this due to strange variations in the surface conduction properties?
Superexpansion bursts:
-- found 32 bursts in data catalog that show a very large photospheric radius expansion (>1000 km) just after burst onset. These superexpansions always lasts for a few seconds and are followed by a moderate expansion phase (10 < r_ph < 100 km) which lasts on a time of order the burst duration (10-1000 s).
-- puzzle: why is the superexpansion duration independent of burst duration? It's probably not due to variations in early time luminosity. Maybe due to ejection of a thin shell that becomes optically thin after a few seconds?
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